Hi Hanif,
Have you solved your problem?
Just sharing, base on my experience it could be :
Maximum character of item description is 20 (SAP B1 9.0 PL05 until PL08 maybe..).
But it's have been enhanced by SAP on version 9.1 PL 01 which can be stored 50 character (I have tested).
Best Regards,
Muh.Ulfah